Jubran Critical Care (2015) 19:272

DOI 10.1186/s13054-015-0984-8

REVIEW Open Access

Pulse oximetry
Amal Jubran1,2

See related review by Jubran, http://ccforum.com/content/3/2/R11

(reduced hemoglobin) using two light wavelengths: 660

Abstract
nm (red) and 940 nm (infrared) [1,2] (Fig. 1). The ratio
Pulse oximetry is universally used for monitoring of absorbance at these wavelengths is calculated and cal-
patients in the critical care setting. This article updates ibrated against direct measurements of arterial oxygen
the review on pulse oximetry that was published in saturation (SaO2) to establish the pulse oximeter’s meas-
1999 in Critical Care. A summary of the recently ure of arterial saturation (SpO2). The waveform, which is
developed multiwavelength pulse oximeters and their available on most pulse oximeters, assists clinicians in
ability in detecting dyshemoglobins is provided. The distinguishing an artifact from the true signal (Fig. 2).
impact of the latest signal processing techniques and
reflectance technology on improving the performance
Accuracy
of pulse oximeters during motion artifact and low
In critically ill patients with SaO2 values of 90 % or
perfusion conditions is critically examined. Finally, data
higher, the mean difference between SpO2 and SaO2
regarding the effect of pulse oximetry on patient
(that is, bias) measured by a reference standard (CO-ox-
outcome are discussed.
imeter) is less than 2 %; the standard deviation of the
differences between the two measurements (that is, pre-
Introduction cision) is less than 3 % [3–5]. The bias and precision of
Pulse oximetry is ubiquitously used for monitoring oxy- pulse oximetry readings, however, worsen when SaO2 is
genation in the critical care setting. By forewarning the lower than 90 % [6,7]. Although pulse oximetry is accur-
clinicians about the presence of hypoxemia, pulse oxi- ate in reflecting one-point measurements of SaO2, it
meters may lead to a quicker treatment of serious hyp- does not reliably predict changes in SaO2, particularly in
oxemia and possibly circumvent serious complications. intensive care unit (ICU) patients [5,8] (Fig. 3).
In this review, I update the principles of pulse oximetry The conventional pulse oximeters use transmission
from my article in 1999 and discuss recent technological sensors in which the light emitter and detector are on
advances that have been developed to enhance the opposing surfaces of the tissue bed. These sensors are
accuracy and clinical applications of this monitoring suitable for use on the finger, toe, or earlobe; when
technique [1]. Finally, available studies evaluating the tested under conditions of low perfusion, finger probes
impact of pulse oximetry on patient outcome will also performed better than other probes [9]. Recently, pulse
be reviewed. oximeter probes that use reflectance technology have
been developed for placement on the forehead [10]. The
Principles of pulse oximetry reflectance sensor has emitter and detector components
The technique of pulse oximetry has been previously de- adjacent to one another, so oxygen saturation is esti-
scribed [1]. Using spectrophotometric methodology, mated from back-scattered light rather than transmitted
pulse oximetry measures oxygen saturation by illuminat- light. In critically ill patients with low perfusion, the bias
ing the skin and measuring changes in light absorption and precision between SpO2 and SaO2 were lower for
of oxygenated (oxyhemoglobin) and deoxygenated blood the forehead reflectance probe than for the finger probe
[11,12]. The superiority of forehead reflectance probes
Correspondence: ajubran@lumc.edu over conventional digital probes, however, was not ob-
1
Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. Veterans served in patients with acute respiratory distress syn-
Affairs Hospital, 111N, 5000 South Fifth Avenue, Hines, IL 60141, USA
2
Loyola University of Chicago Stritch School of Medicine, 2160 South First drome (ARDS) during a positive end-expiratory pressure
Avenue, Maywood, IL 60153, USA (PEEP) recruitment maneuver [13].
© 2015 Jubran. This is an Open Access article distributed under the terms of the Creative Commons Attribution License
(http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://
creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Jubran Critical Care (2015) 19:272 Page 2 of 7

Fig. 1 Transmitted light absorbance spectra of four hemoglobin species: oxyhemoglobin, reduced hemoglobin, carboxyhemoglobin,
and methemoglobin

Fig. 2 Common pulsatile signals on a pulse oximeter. (Top panel) Normal signal showing the sharp waveform with a clear dicrotic notch.
(Second panel) Pulsatile signal during low perfusion showing a typical sine wave. (Third panel) Pulsatile signal with superimposed noise artifact
giving a jagged appearance. (Bottom panel) Pulsatile signal during motion artifact showing an erratic waveform. Reprinted with permission from
BioMed Central Ltd [1]
Jubran Critical Care (2015) 19:272 Page 3 of 7

Fig. 3 Changes in oxygen saturation measured by pulse oximetry (SpO2) compared with arterial oxygen saturation measured by a CO-oximeter
(SaO2) in critically ill patients. The pulse oximeter consistently overestimated the actual changes of SaO2. Reprinted with permission from BioMed
Central Ltd [8]

The response time of conventional oximeter probes seconds for the forehead probe and 100 seconds for the
varies; ear probes respond quicker to a change in O2 finger probe. After mask ventilation was started, the
saturation than finger probes [14,15]. A recent study lengths of time it took to detect an increase in SpO2 to
compared the response time of the conventional finger 100 % (re-saturation response time) were 23.2 seconds
probe with the reflectance forehead probe in patients for the forehead probe and 28.9 seconds for the finger
undergoing general anesthesia [16] (Fig. 4). The lengths probes. The investigators speculated that the shorter
of time it took to detect a decrease in SpO2 to 90 % after response time with the reflectance forehead probe was
apnea was induced (desaturation response time) were 94 most likely due to the location of the probe rather than

Fig. 4 Oxygen saturation measured with pulse oximetry (SpO2) using transmittance finger probe (diamond) and reflectance forehead probe
(squares) during apnea and mask ventilation with 100% O2. The reflectance probe showed faster responses than the transmission probe at every
measurement point. *P < 0.05 between the two groups. Reprinted with permission from Wiley [16]
Jubran Critical Care (2015) 19:272 Page 4 of 7

to the workings of the reflectance technology. The fore- unable to measure COHb levels. In patients evaluated
head probe monitors O2 saturation from the supraorbital in the emergency department with suspected carbon mon-
artery in which blood flow is abundant and is less likely oxide poisoning, the bias between pulse CO-oximetric
to be affected by vasoconstriction than is a peripheral measurement of COHb and laboratory CO-oximetric
artery [17]. measurement of COHb was less than 3 % [22,23]. The
limits of agreement between the measurements, however,
Limitations were large (−11.6 % to 14.14 %) [23], leading some authors
Oximeters have limitations which may result in errone- to conclude that these new pulse CO-oximeters may not
ous readings [15] (Table 1). Because of the sigmoid be used interchangeably with standard laboratory mea-
shape of the oxyhemoglobin dissociation curve, oximetry surements of COHb [22–24].
may not detect hypoxemia in patients with high arterial Inaccurate readings with pulse oximetry have been re-
oxygen tension (PaO2) levels [1,18]. ported with intravenous dyes used for diagnostic pur-
Conventional pulse oximeters can distinguish only two poses, low perfusion states (that is, low cardiac output,
substances: reduced hemoglobin and oxyhemoglobin; it vasoconstriction, and hypothermia), pigmented subjects
assumes that dyshemoglobins—such as carboxyhemoglo- and in patients with sickle cell anemia [1,6,25,26]. Be-
bin (COHb) and methemoglobin (MetHb)—are absent cause the two wavelengths (660 and 940 nm) that pulse
(Fig. 1). Studies showed that the presence of elevated oximeters use to measure SpO2 can be produced by vari-
levels of COHb and MetHb could affect the accuracy ous ambient light sources, the presence of such sources
of SpO2 readings [1,19]. Accordingly, multiwavelength could produce false SpO2 readings. To test the accuracy
oximeters that are capable of estimating blood levels of of pulse oximetry in the presence of ambient light, Fluck
COHb and MetHb have recently been designed [20]. In and colleagues [27] performed a randomized controlled
healthy volunteers, the accuracy of a multiwavelength trial in healthy subjects in which SpO2 measurements
oximeter (Masimo Rainbow-SET Rad-57 Pulse CO- were obtained in a photographic darkroom under five
oximeter; Masimo Corporation, Irvine, CA, USA) in separate light sources: quartz-halogen, infrared, incan-
measuring dyshemoglobins was evaluated by inducing car- descent, fluorescent, and bilirubin light [27]. The largest
boxyhemoglobinemia (levels range from 0 % to 15 %) and difference in SpO2 between the control condition (that
methemoglobinemia (levels range from 0 % to 12 %) [20]. is, complete darkness) and any of the five light sources
Bias between COHb levels measured with the pulse CO- was less than 5%. Nail polish can interfere with pulse ox-
oximeter and COHb levels measured with the laboratory imetry readings [28]. In 50 critically ill patients requiring
CO-oximeter (standard method) was −1.22 %; the corre- mechanical ventilation, Hinkelbein and colleagues [29]
sponding precision was 2.19 %. Bias ± precision of MetHB found that the mean difference between SpO2 and SaO2
measured with the pulse CO-oximeter and MetHb mea- was greatest for black (+1.6 % ± 3.0 %), purple (+1.2 % ±
sured with the laboratory CO-oximeter was 0.0 % ± 2.6 %), and dark blue (+1.1 % ± 3.5 %) nail polish; limits
0.45 %. The accuracy of pulse CO-oximeters in measuring of agreement ranged from 6 % (unpainted fingernail) to
COHb levels was also assessed during hypoxia [21]. In 12 14.4 % (dark blue) (Fig. 5). Rotating the oximeter finger
healthy volunteers, the pulse CO-oximeter was accurate probe by 90 ° did not eliminate the error induced with
in measuring COHb at an SaO2 of less than 95 % (bias nail polish.
of −0.7 % and precision of 4.0 %); however, when the Motion artifact is considered an important cause of
SaO2 dropped below 85%, the pulse CO-oximeter was error and false alarms [30–33]. In the 1990s, several sig-
nal processing techniques were incorporated in pulse
Table 1 Limitations of pulse oximetry oximeters in an attempt to reduce motion artifact [34–38].
Shape of oxygen dissociation curve One such technique is Masimo signal extraction technol-
Dyshemoglobins ogy (SET™) [39]. During motion and hypoxia, the Masimo
- Carboxyhemoglobin SET oximeter performed better than the Agilent Viridia
- Methemoglobin
24C (Agilent Technologies, Santa Clara, CA, USA), the
Datex-Ohmeda 3740 (Datex-Ohmeda, Madison, WI, USA),
Dyes
and the Nellcor N-395 (Covidien Corporation, Dublin,
Low perfusion state Ireland) oximeters [34].
Skin pigmentation The knowledge about pulse oximetry among clini-
Anemia cians continues to be limited. When 551 critical care
Nail polish nurses were recently interviewed, 37 % of them did not
Motion artifact
know that oximeters were more likely to be inaccurate
during patient motion, 15 % did not know that poor
Limited knowledge of the technique
signal quality can produce inaccurate readings, and
Jubran Critical Care (2015) 19:272 Page 5 of 7

Fig. 5 Bias of O2 saturation pulse oximetry (SpO2) and arterial O2 saturation (SaO2) of various nail polish colors in critically ill patients. Thick
horizontal lines represent mean bias, the whiskers represent maximum and minimum bias; the bottom and top of the boxes represent the first
and third quartiles. *P < 0.05 ,**P < 0.01 when compared with arterial oxygen saturation. Reprinted with permission from Elsevier Inc. [29]

30 % considered that SpO2 readings could be used in an SpO2 of 92 % is reasonable for ensuring satisfactory
lieu of arterial blood gas samples when managing ICU oxygenation in Caucasian patients [6]. To determine
patients [40]. whether the ratio of SpO2 to FIO2 (S/F) can be used as a
surrogate for the ratio of PaO2 to FIO2 (P/F), SpO2 and
Clinical applications PaO2 data from 1,074 patients with acute lung injury or
Pulse oximetry can provide an early warning of hypoxemia ARDS who were enrolled in two large clinical trials were
[41,42]. In the largest randomized trial involving more than compared [47]. An S/F ratio of 235 predicted a P/F ratio
20,000 perioperative patients, rates of incidence of hypox- of 200 (oxygenation criterion for ARDS), a sensitivity of
emia (SpO2 of less than 90 %) were 7.9 % in patients who 0.85, and a specificity of 0.85. An S/F ratio of 310
were monitored with pulse oximetry and only 0.4 % in pa- reflected a P/F ratio of 300 (oxygenation criterion for
tients without an oximeter [43]. The anesthesiologists re- acute lung injury), a sensitivity of 0.91, and a specificity
ported that oximetry led to a change in therapy on at least of 0.56. In patients undergoing surgery, the S/F ratio was
one occasion in up to 17 % of the patients. Using 95,407 shown to be a reliable proxy for the P/F ratio (correl-
electronically recorded pulse oximetry measurements from ation coefficient (r) of 0.46), especially in those patients
patients who underwent non-cardiac surgery at two hospi- requiring PEEP levels of greater than 9 cm H2O
tals, Ehrenfeld and colleagues [44] reported that during the (r = 0.68) and those patients with a P/F ratio of 300 or
intraoperative period, 6.8 % of patients had a hypoxemic less (r = 0.61) [48]. In the ICU, the S/F ratio can also be
event (SpO2 of less than 90) and 3.5 % of patients had a se- a surrogate measure for the P/F ratio when calculating
vere hypoxemic event (SpO2 of not more than 85 %) lasting the sequential organ failure assessment score, which
more than 2 minutes. Hypoxemic events occurred mostly measures the severity of organ dysfunction in critically
during the induction or emergent phase of anesthesia; these ill patients [49].
time periods are consistent with the clinical view that
anesthesia-transitional states are high-risk periods for hyp-
oxemia [45]. In patients undergoing gastric bypass surgery, Cost-effectiveness
continuous monitoring of SpO2 revealed that episodic hyp- Studies have shown that the presence of pulse oximetry
oxemia (SpO2 of less than 90 % for at least 30 seconds) oc- may reduce the number of arterial blood gas samples
curred in all patients. For each patient, desaturation lasted obtained in the ICU and in the emergency department
as long as 21 ± 15 minutes [46]. [50,51]. However, the lack of incorporating explicit
Pulse oximetry has been shown to be reliable in titrat- guidelines for the appropriate use of pulse oximetry
ing the fractional inspired oxygen concentration (FIO2) may lessen the cost-effectiveness of pulse oximetry in
in patients requiring mechanical ventilation; aiming for the ICU [1].
Jubran Critical Care (2015) 19:272 Page 6 of 7

Effect on outcome improved the performance of pulse oximeters under

To date, the largest randomized controlled trial that conditions of motion artifact and low perfusion. Multi-
has evaluated the impact of pulse oximetry on outcome wavelength oximeters may prove to be useful in detect-
was the study by Moller and colleagues [43] in 20,802 ing dyshemoglobinemia. Monitoring with pulse oximetry
surgical patients. Although myocardial ischemia occurred continues to be a critical component of standard of care
less frequently in the oximetry than the control group, the of critically ill patients despite the paucity of data that
numbers of post-operative complications and hospital such devices improve outcome.
deaths were similar in the two groups [43].
In a more recent randomized study in 1,219 post- Abbreviations
ARDS: acute respiratory distress syndrome; COHb: carboxyhemoglobin;
operative patients, Ochroch and colleagues [52] assessed
FIO2: fractional inspired oxygen concentration; ICU: intensive care unit;
the impact of pulse oximetry on the rate of transfer to the MetHb: methemoglobin; PaO2: arterial oxygen tension; PEEP: positive
ICU from a post-surgical care floor. Upon admission to end-expiratory pressure; P/F: PaO2-to-FIO2 ratio; r: correlation coefficient;
SaO2: arterial oxygen saturation; SET: signal extraction technology; S/F: SpO2-
the study floor, patients were randomly assigned to receive
to-FIO2 ratio; SpO2: oxygen saturation measured by pulse oximetry.
monitoring with a pulse oximeter either continuously
(n = 589) (oximeter group) or intermittently (n = 630) Competing interests
according to clinical needs as judged by a nurse or a phys- The author declares that he has no competing interests.
ician (control group). The percentages of patients trans-
ferred to the ICU were similar in the oximeter group and
the control group (6.7 % versus 8.5 %). A lower rate of
ICU transfers for pulmonary complications was noted in References
the oximeter group. For those patients who required ICU 1. Jubran A. Pulse oximetry. Crit Care. 1999;3:R11–7.
transfer, the estimated cost from enrollment to completion 2. Wukitsch MW, Petterson MT, Tobler DR, Pologe JA. Pulse oximetry: analysis
of theory, technology, and practice. J Clin Monit. 1988;4:290–301.
of the study was less in the oximeter group ($15,481) than 3. Wouters PF, Gehring H, Meyfroidt G, Ponz L, Gil-Rodriguez J, Hornberger C,
in the control group ($18,713) despite the older age and et al. Accuracy of pulse oximeters: the European multi-center trial. Anesth
higher comorbidity of the former. The authors speculate Analg. 2002;94(1 Suppl):S13–6.
4. Webb RK, Ralston AC, Runciman WB. Potential errors in pulse oximetry, II.
that reduction in pulmonary transfers to the ICU may be Effects of changes in saturation and signal quality. Anaesthesia.
due to the earlier recognition and treatment of post- 1991;46:207–12.
operative pulmonary complications. 5. Van de Louw A, Cracco C, Cerf C, Harf A, Duvaldestin P, Lemaire F, et al.
Accuracy of pulse oximetry in the intensive care unit. Intensive Care Med.
The lack of demonstrable benefit of pulse oximetry on 2001;27:1606–13.
outcome in clinical trials may be due to the signal-to- 6. Jubran A, Tobin MJ. Reliability of pulse oximetry in titrating supplemental
noise ratio [41,53]. Because the outcome under evalu- oxygen therapy in ventilator-dependent patients. Chest. 1990;97:1420–5.
7. Pulse oximeters. Health Devices. 1989;18:185–99, 206–19, 222–30.
ation (readmission to the ICU, myocardial infarction, or 8. Perkins GD, McAuley DF, Giles S, Routledge H, Gao F. Do changes in pulse
death) is rare, a huge number of patients are needed to oximeter oxygen saturation predict equivalent changes in arterial oxygen
show a reduction in these events [41]. To demonstrate a saturation? Crit Care. 2003;7:R67.
9. Clayton DG, Webb RK, Ralston AC, Duthie D, Runciman WB. Pulse oximeter
reduction in complications in the study by Moller and probes. A comparison between finger, nose, ear and forehead probes under
colleagues, for example, a 23-fold increase in enrollment conditions of poor perfusion. Anaesthesia. 1991;46:260–5.
would have been required [41,53]. 10. Branson RD, Mannheimer PD. Forehead oximetry in critically ill patients: the
case for a new monitoring site. Respir Care Clin N Am. 2004;10:359–67.
The fact that randomized trials failed to demonstrate 11. Fernandez M, Burns K, Calhoun B, George S, Martin B, Weaver C. Evaluation
that routine monitoring with pulse oximetry improved of a new pulse oximeter sensor. Am J Crit Care. 2007;16:146–52.
patient outcome has not stopped anesthesiologists from 12. Schallom L, Sona C, McSweeney M, Mazuski J. Comparison of forehead and
digit oximetry in surgical/trauma patients at risk for decreased peripheral
using pulse oximeters [53,54]. When surveyed, 94 % of perfusion. Heart Lung. 2007;36:188–94.
the anesthesiologists in the study by Moller and col- 13. Hodgson CL, Tuxen DV, Holland AE, Keating JL. Comparison of forehead Max-
leagues [43] considered the pulse oximeters to be helpful Fast pulse oximetry sensor with finger sensor at high positive end-expiratory
pressure in adult patients with acute respiratory distress syndrome. Anaesth
in guiding clinical management. They believed that Intensive Care. 2009;37:953–60.
maintaining oxygenation within the physiologic limits 14. Young D, Jewkes C, Spittal M, Blogg C, Weissman J, Gradwell D. Response
with the help of pulse oximetry might help avert irre- time of pulse oximeters assessed using acute decompression. Anesth Analg.
1992;74:189–95.
versible injury. It is this perspective that has made pulse 15. Jubran A. Pulse oximetry. In: Tobin MJ, editor. Principles and Practice of
oximetry a crucial part of standard of care despite the Intensive Care Monitoring. New York: McGraw-Hill, Inc; 1998. p. 261–87.
absence of proven efficacy [41]. 16. Choi SJ, Ahn HJ, Yang MK, Kim CS, Sim WS, Kim JA, et al. Comparison of
desaturation and resaturation response times between transmission and
reflectance pulse oximeters. Acta Anaesthesiol Scand. 2010;54:212–7.
Conclusions 17. MacLeod DB, Cortinez LI, Keifer JC, Cameron D, Wright DR, White WD, et al.
Pulse oximetry is universally used for monitoring The desaturation response time of finger pulse oximeters during mild
hypothermia. Anaesthesia. 2005;60:65–71.
respiratory status of patients in the ICU. Recent ad- 18. Ralston AC, Webb RK, Runciman WB. Potential errors in pulse oximetry, I.
vances in signal analysis and reflectance technology have Pulse oximeter evaluation. Anaesthesia. 1991;46:202–6.
Jubran Critical Care (2015) 19:272 Page 7 of 7

19. Buckley RG, Aks SE, Eshom JL, Rydman R, Schaider J, Shayne P. The pulse 45. Hare GM, Kavanagh BP. Hypoxemia during surgery: learning from history,
oximetry gap in carbon monoxide intoxication. Ann Emerg Med. science, and current practice. Can J Anaesth. 2010;57:877–81.
1994;24:252–5. 46. Gallagher SF, Haines KL, Osterlund LG, Mullen M, Downs JB. Postoperative
20. Barker SJ, Curry J, Redford D, Morgan S. Measurement of carboxyhemoglobin hypoxemia: common, undetected, and unsuspected after bariatric surgery.
and methemoglobin by pulse oximetry: a human volunteer study. J Surg Res. 2010;159:622–6.
Anesthesiology. 2006;105:892–7. 47. Rice TW, Wheeler AP, Bernard GR, Hayden DL, Schoenfeld DA, Ware LB,
21. Feiner JR, Rollins MD, Sall JW, Eilers H, Au P, Bickler PE. Accuracy of et al. Comparison of the SpO2/FIO2 ratio and the PaO2/FIO2 ratio in
carboxyhemoglobin detection by pulse CO-oximetry during hypoxemia. patients with acute lung injury or ARDS. Chest. 2007;132:410–7.
Anesth Analg. 2013;117:847–58. 48. Tripathi RS, Blum JM, Rosenberg AL, Tremper KK. Pulse oximetry saturation
22. Sebbane M, Claret PG, Mercier G, Lefebvre S, Thery R, Dumont R, et al. to fraction inspired oxygen ratio as a measure of hypoxia under general
Emergency department management of suspected carbon monoxide anesthesia and the influence of positive end-expiratory pressure. J Crit Care.
poisoning: role of pulse CO-oximetry. Respir Care. 2013;58:1614–20. 2010;25:542.e9-13.
23. Touger M, Birnbaum A, Wang J, Chou K, Pearson D, Bijur P. Performance of 49. Pandharipande PP, Shintani AK, Hagerman HE, St Jacques PJ, Rice TW,
the RAD-57 pulse CO-oximeter compared with standard laboratory Sanders NW, et al. Derivation and validation of Spo2/Fio2 ratio to impute
carboxyhemoglobin measurement. Ann Emerg Med. 2010;56:382–8. for Pao2/Fio2 ratio in the respiratory component of the Sequential Organ
24. Maisel WH, Lewis RJ. Noninvasive measurement of carboxyhemoglobin: Failure Assessment score. Crit Care Med. 2009;37:1317–21.
how accurate is accurate enough? Ann Emerg Med. 2010;56:389–91. 50. Le Bourdelles G, Estagnasie P, Lenoir F, Brun P, Dreyfuss D. Use of a pulse
25. Saito S, Fukura H, Shimada H, Fujita T. Prolonged interference of blue dye oximeter in an adult emergency department: impact on the number of
‘patent blue’ with pulse oximetry readings. Acta Anaesthesiol Scand. arterial blood gas analyses ordered. Chest. 1998;113:1042–7.
1995;39:268–9. 51. Solsona JF, Marrugat J, Vazquez A, Masdeu G, Alvarez F, Nolla J. Effect of
26. Comber JT, Lopez BL. Evaluation of pulse oximetry in sickle cell anemia pulse oximetry on clinical practice in the intensive care unit. Lancet.
patients presenting to the emergency department in acute vasoocclusive 1993;342:311–2.
crisis. Am J Emerg Med. 1996;14:16–8. 52. Ochroch EA, Russell MW, Hanson 3rd WC, Devine GA, Cucchiara AJ, Weiner
27. Fluck Jr RR, Schroeder C, Frani G, Kropf B, Engbretson B. Does ambient light MG, et al. The impact of continuous pulse oximetry monitoring on intensive
affect the accuracy of pulse oximetry? Respir Care. 2003;48:677–80. care unit admissions from a postsurgical care floor. Anesth Analg.
28. Cote CJ, Goldstein EA, Fuchsman WH, Hoaglin DC. The effect of nail polish 2006;102:868–75.
on pulse oximetry. Anesth Analg. 1988;67:683–6. 53. Shah A, Shelley KH. Is pulse oximetry an essential tool or just another
29. Hinkelbein J, Genzwuerker HV, Sogl R, Fiedler F. Effect of nail polish on distraction? The role of the pulse oximeter in modern anesthesia care. J Clin
oxygen saturation determined by pulse oximetry in critically ill patients. Monit Comput. 2013;27:235–42.
Resuscitation. 2007;72:82–91. 54. Pedersen T, Nicholson A, Hovhannisyan K, Moller AM, Smith AF, Lewis SR.
30. Reich DL, Timcenko A, Bodian CA, Kraidin J, Hofman J, DePerio M, et al. Pulse oximetry for perioperative monitoring. Cochrane Database Syst Rev.
Predictors of pulse oximetry data failure. Anesthesiology. 1996;84:859–64. 2014;3, CD002013.
31. Moller JT, Pedersen T, Rasmussen LS, Jensen PF, Pedersen BD, Ravlo O, et al.
Randomized evaluation of pulse oximetry in 20,802 patients: I. Design,
demography, pulse oximetry failure rate, and overall complication rate.
Anesthesiology. 1993;78:436–44.
32. Runciman WB, Webb RK, Barker L, Currie M. The Australian Incident
Monitoring Study. The pulse oximeter: applications and limitations - an
analysis of 2000 incident reports. Anaesth Intensive Care. 1993;21:543–50.
33. Rheineck-Leyssius AT, Kalkman CJ. Influence of pulse oximeter lower alarm
limit on the incidence of hypoxaemia in the recovery room. Br J Anaesth.
1997;79:460–4.
34. Barker SJ. ‘Motion-resistant’ pulse oximetry: a comparison of new and old
models. Anesth Analg. 2002;95:967–72.
35. Petterson MT, Begnoche VL, Graybeal JM. The effect of motion on pulse
oximetry and its clinical significance. Anesth Analg.
2007;105(6 Suppl):S78–84.
36. Next-generation pulse oximetry. Health Devices. 2003;32:49–103.
37. Barker SJ, Shah NK. The effects of motion on the performance of pulse
oximeters in volunteers (revised publication). Anesthesiology.
1997;86:101–8.
38. Dumas C, Wahr JA, Tremper KK. Clinical evaluation of a prototype motion
artifact resistant pulse oximeter in the recovery room. Anesth Analg.
1996;83:269–72.
39. Pollard V, Prough DS. Signal extraction technology: a better mousetrap?
Anesth Analg. 1996;83:213–4.
40. Giuliano KK, Liu LM. Knowledge of pulse oximetry among critical care nurses.
Dimens Crit Care Nurs. 2006;25:44–9.
41. Jubran A, Tobin MJ. Monitoring during mechanical ventilation. In: Tobin MJ,
editor. Principles and Practice of Mechanical Ventilation. New York: McGraw-Hill,
Inc; 2013. p. 261–87.
42. Pretto JJ, Roebuck T, Beckert L, Hamilton G. Clinical use of pulse oximetry:
official guidelines from the Thoracic Society of Australia and New Zealand.
Respirology. 2014;19:38–46.
43. Moller JT, Johannessen NW, Espersen K, Ravlo O, Pedersen BD, Jensen PF,
et al. Randomized evaluation of pulse oximetry in 20,802 patients: II.
Perioperative events and postoperative complications. Anesthesiology.
1993;78:445–53.
44. Ehrenfeld JM, Funk LM, Van Schalkwyk J, Merry AF, Sandberg WS, Gawande A.
The incidence of hypoxemia during surgery: evidence from two institutions.
Can J Anaesth. 2010;57:888–97.